Removal of polyester oligomers with chlorofluoroalkanes and methylene chloride treatment of polyester fibers

ABSTRACT

PROCESS FOR THE IMPROVEMENT OF THE PROCESSING AND DYEING PROPERTIES OF TEXTILE MATERIALS CONSISTING OF OR CONTAINING HIGH MOLECULAR POLYESTERS BY TREATING THESE MATERIALS WITH A SOLVENT MIXTURE OF HALOGENATED METHANE OR ETHANE DERIVATIVES OF THE GENERAL FORMULA   R-F   IN WHICH R REPRESENTS A RADICAL OF THE FORMULA   FCL2C-CFCL-   OR CL3C-, AND METHYLENE CHLORIDE, CONTAINING BOTH THE COMPONENTS IN A WEIGHT RATIO OF FROM 30:70 TO 70:30, PREFERABLY OF FROM 45:55 TO 55:45.

' United States Patent US. Cl. 8-17 7 Claims ABSTRACT OF THE DISCLOSUREProcess for the improvement of the processing and dyeing properties oftextile materials consisting of or containing high molecular polyestersby treating these materials with a solvent mixture of halogenatedmethane or ethane derivatives of the general formula in which Rrepresents a radical of the formula or Cl C, and methylene chloride,containing both the components in a weight ratio of from 30:70 to 70:30,preferably of from 45 :55 to 55:45.

The present invention provides a process for the improvement of theprocessing and dyeing properties of polyester textile materials.

In a side reaction of the synthesis of polyesters, oligomers are formedwhich may result in certain troubles. These disturbances are caused bydeposits on the fibre, which then impair the dyeability of the goods, aswell as on machine parts. Besides cyclic oligomers, also linearoligomers have been detected (cf. Zeitschrift fiir die gesamteTextil-Industrie, vol. 71/7 (1969), page 488).

Generally, the portion of these oligomers in the polyester materialamounts up to 5% by weight. In the course of dyeing processes,especially in the dyeing under hightemperature or thermofixationconditions these oligomers may emerge from the polymer fibre. Sinceoligomers cannot be dyed with the disperse dyestuffs generally used forthe dyeing of polyester fibres, fair non-dyed spots may remain on thedyed goods. Moreover, dyed polyester fibres containing oligomers provokethe formation of considerable amounts of dust during the spinningprocess, which cause production trouble. Very often, oligomer depositsare also found in the liquor pumps of the dyeing machines resulting ininterruptions of the production and further waste of time by cleaningoperations.

It has therefore been tried to remove such oligomers from the polyestermaterial by means of diiferent aftertreatments methods. For example, itis known that oligomers may partly be eliminated by means of rinsingwith hot water or by an alkaline reductive after-treatment in theprescence of a tenside, for example a fatty acid polyglycol ester, andat elevated temperatures. Furthermore, it is known that oligomers may beeliminated by a treatment of the textile material with organic solvents,but this process has been of no importance in practice since itdeteriorates the textile processing properties of the fibres, and, incase the material is dyed, also the dyestuff is dissolved out of thefibres in considerable amounts. Thus, the removal of oligomers forexample with dioxane is known. However, after 2 hours of extraction ofthe "ice polyester fibre material with dioxane, only 1.5% of theoligomers are removed. This amount increases after 32 hours only andattains about 4% after 64 hours only. Methylene chloride exhibits a verygood dissolving power for oligomers from high molecular polyesters;however, this causes considerable damage to the fibres resulting in ashrinkage of the fabrics. In case a dyed polyester fabric is treatedwith methylene chloride, besides the damage of the fibres also aconsiderable amount of the dyestuffs already fixed on the fibre isdissolved out.

It has now been found that the processing and dyeing properties oftextile materials made from or containing high molecular polyesters canbe improved in a very simple and economic manner by treating thesematerials with a solvent mixture of halogenated methane or ethanederivatives of the general formula in which R represents a radical ofthe formula -FCl CCFClor Cl C, and methylene chloride, which mixturecontains both the components in a weight ratio of from 30:70 to 70:30,preferably of from 45:55 to 55:45.

In the process of the invention, an azeotropic mixture of 50.5% byweight of 1,2,2-trifiuoro-trichloro-ethane and 49.5% by weight ofmethylene chloride is advantageously used as solvent mixture. Theboiling point of this mixture is 37 C. at 760 mm. Hg. The use of thismixture in industrial practice is specially recommended, since thisazeotropic mixture behaves as uniform substance both in the liquid andin the vapor phase. Hence, there is no decrease in the amount of one ofthe components during the treatment and the subsequent recovery of thesolvent.

The treatment with the solvent mixtures is advantageously carried out attemperatures of from about 10 to 60 0, preferably of from about 20 to 40C. In case the treatment temperature is above the boiling point of thesolvent, the treatment should be carried out in pressure-proofapparatuses under the pressure establishing itself in each special case.Furthermore, the treatment of the textile material may be also carriedout with reflux of the solvent mixture.

The time of treatment necessary for the elimination of the oligomersdepends above all on their amount and the temperature of the treatmentmedium applied. Generally, a treatment of from 1 to 15 minutes issufiicient. However, it is also possible to continue the treatment withthe solvent mixture for a longer period without damaging the textilematerial.

The solvent mixture is used at least in an amount necessary for thecomplete elimination of the oligomers from the textile material. Theoptimum amount to be used in each case can easily be determined inpreliminary tests. Generally, a goods-to-liquor ratio of from about 1:5to 1:50 is recommended, and it is advantageous to ensure a goodcirculation of the liquor.

The process of the invention may be carried out in an equipment asnormally used. However, these apparatuses should be gas-proof in view ofthe considerable vapor pressure of the solvent mixtures already at roomtemperature. Thus, the process of the invention may be carried out inapparatuses as normally used for dry-cleaning. In case the polyesteryarns are on cross-wound bobbins, it is possible to treat them in anormal dyeing apparatus for cross-wound bobbins; a continuous recyclingof the solvent mixture, however, must be ensured in this case. Theprocess of the invention may be carried out batchwise or continuously,the latter being especially advantageous in case the textile material ispresent in the form of woven or knit fabrics.

When the oligomer content in the solvent mixture is exceedingly high,the solvent mixture has to be replaced by a fresh one. This too may bedetermined by simple preliminary tests in each case. The treatment mayalso be carried out in several serial-connected baths. Anotheradvantageous method is to heat the solvent mixture to boilingtemperature, to contact the textile material wih the solvent vapors, tocondense these vapors on the material and to recirculate the condensateinto the boiling solvent mixture. This method is especially advantageousbecause the textile material is always contacted with fresh solventmixture. The solvent mixture used is recovered by distillation andcooling, and the solvent mixture thus recovered may be used again forfurther treatment. Hence it is possible to work with a limited amount ofsolvent; smaller losses being balanced if necessary.

. As high molecular polyesters, especiallypolyethyleneglycol-terephthalate and modifiedpolyethylene-glycolterephthalates are used which may also be blendedwith other fibrous materials, especially with cellulose fibres or wool.The textile material may be available in a variety of forms, for exampleflocks, combed material, yarns, woven and knit fabrics or fleeces.

The process of the invention is suitable for the treatment of bothundyed and dyed or printed polyester materials. For a successful resultof the process of the invention it is irrelevant whether the textilematerial has been dyed or printed with disperse dyestuffs, azodeveloping dyestuffs, vat dyestuffs or sulfuric acid esters of leuco vatdyestufis.

The solvent mixtures may also be used for the removal of oligomerdeposits on textile machines.

By treating the textile material according to the process of theinvention, the oligomers contained in the material are completelydissolved out. This treatment neither results in a damage of the fibrenor in the elimination of the dyestuif of dyed or printed textilematerials during the treatment. The solvent treatment of the inventionensures at the same time the fixation of the fibre as up to now has beenpossible only by means of a corresponding heat treatment.

In comparison with the method applied up to now using aqueous media, theprocess of the invention is advantageous in that the treatment may becarried out at substantially lower temperatures. For this reason and onaccount of the substantially lower specific heat of the solvent mixturesused according to the process of the invention, the energy requirementsof the process of the invention are also substantially lower than in thecase of the conventional process. Further energy is economized when thetextile material is dried, since the solvent mixtures used require asubstantially lower evaporation heat than water. A further advantage ofthe process of the invention over the conventional process resides inthe fact that there is caused nearly no corrosion of the equipmentparts. Moreover, the process of the invention brings about no wastewater problems, since the solvent mixture may be recovered in a simplemanner, and the oligomer residue may easily be removed, for example byburning. This is a further advantage of the process of the inventionover the conventional method.

In comparison with the known processes using organic solvents, theprocess of the invention provides the advantage of preventing fibredamages resulting for example in a shrinkage of the fabric. Furthermore,there is no dyestuff being dissolved out of the material by thetreatment of dyed or printed textile materials. The solvent mixturesused are also considerably less toxic than the solvents used up to now.The treatment time is substantially shorter than in conventionalprocesses, and a considerably greater amount of oligomers is eliminatedthan in case organic solvents are used for this purpose as this wasnormal up to now. A further great advantage resides in the fact that thetextile materials treated according to the process of the invention neednot be fixed, which means economizing considerable ener-gy amounts. I

The following examples illustrate the invention.

EXAMPLE 1 1 kg. of a dyeing produced under HT conditions on a tafettafabric made from polyethylene-glycol-terephthalate with 2% of a dispersedyestuff of the following formula f) NH;

and showing fair spots due to deposited oligomers of the polyestermaterial, was treated for 10 minutes at room temperature with 10 litresof an azeotropic mixture of 50.5% by weight of1,2,Z-trifiuoro-trichloro-ethane and 49.5% by weight of methylenechloride. After this treatment, no oligomer deposits could be detectedon the goods, and no dyestufl. was dissolved out of the fabric.

EXAMPLE 2 20 g. of a knit fabric made from texturizedpolyethyleneglycol-terephthalate fibres were dyed for minutes at 120 C.with 1.4% of a disperse dyestuff of the following 2% of a dispersedyestuff of the formula rnN 0 OH I II 1 H YP IH:

1 g./litre of a dispersing agent of the naphthalene-sulfonicacid/formaldehyde condensate type (as sodium salt) and 0.5 g./litre of acommercial carrier on the basis of an ester, at a pH of 5.5 (adjustedwith acetic acid) and a goods-to-liquor ratio of 1:20. After rinsing anddrying, half of the dyed fabric was treated for 15 minutes at roomtemperature in ml. of methylene chloride, the other half was treatedunder the same conditions in a mixture of 45 ml. of1,2,Z-trifluoro-trichoro-ethane and 55 ml. of methylene chloride.Subsequently, both pieces were dried 1n air.

The dyed fabric treated only with methylene chloride showed very deepcreases, and in this case a very heavy bleeding of the dyestuffs off thedyeing into the treatment bath was observed. The fabric treated with theabove mixture was completely smooth, and no bleeding into the bath couldbe observed; oligomers could neither be detected any more.

EXAMPLE 3 The warp and weft of two non-fixed taffeta fabrics made frompolyethylene-glycol terephthalate fibres (size about 30 x 30 cm. each)were marked in intervals of about 20 cm. Subsequently, the fabric wastreated as follows:

(a) immersed for 15 minutes at room temperature in methylene chloride;goods-to-liquor ratio 1:20,

(b) immersed for 15 minutes at room temperature in a mixture of 50% ofmethylene chloride and 50% of 1,2,2 trifluorotrichloro-ethane;goods-to-liquor ratio 1:20.

After this treatment, both of the fabrics were dried in air. Afterdrying, it could be observed that the fabric treated only with methylenechloride was very heavily creased, while the other fabric was completelysmooth. When measuring the intervals marked, the following shrinkagevalues resulted:

fabric (a): 4.8% and 5% shrinkage of the warp and the weft respectively,fabric (b): no shrinkage.

used.

EXAMPLE 4 20 g. of a knit fabric made from texturizedpolyethylene-glycol-terephthalate fibres were dyed for 90 minutes at 125C. with 0.9% of a disperse dyestutf of the formula 0.4% of a dyestulf ofthe formula HrN (HI and 1.2% of a dyestulf of the formula 11 11,0o,N--N= @mcmomom at a liquor ratio of 1:30. The pH of the bath wasadjusted to 5.1 by means of acetic acid.

After rinsing and drying, half of the dyeing was treated for 15 minutesat room temperature with 100 ml. of methylene chloride, the other half,under the same conditions, with a mixture of 50 ml. offiuoro-trichloro-methane and 50 ml. of methylene chloride. Subsequently,both pieces were dried in air.

It was observed that the dyed fabric treated only with methylenechloride was very heavily creased and that there was also bleeding ofthe dyestuffs off the dyeing into the solvent, i.e. dissolution of thedyestuffs in the solvent, so that the solvent was coloured to a greatextent. In the other case, where the fluoro-trichloro-methane/methylenechloride mixture was used, a completely smooth fabric was obtained andthe solvent mixture was not coloured. No oligomer deposits on the fabriccould be detected after the treatment.

We claim:

1. A process for the improvement of the processing and dyeing ofpolyester textiles which comprises applying to these textiles a solventmixture of halogenated methane or ethane derivatives of the generalformula in which R represents a radical of the formula FCbC- CFCl-- orCl C, and methylene chloride, containing both the components in a weightratio of from 30:70 to :30.

2. A process as claimed in claim 1, which comprises using a solventmixture containing both the components in a weight ratio of from 45:55to 55:45.

3. A process as claimed in claim 1, which comprises using as solventmixture an azeotropic mixture of 50.5% by weight of1,2,2--trifluoro-trichloro-ethane and 49.5% by weight of methylenechloride.

4. A process as claimed in claim 1, which comprises carrying out thetreatment at temperatures of from about 10 to 60 C.

5. A process as claimed in claim 4, which comprises carrying out thetreatment at temperatures of from 20 to 40 C.

6. A process as claimed in claim 1, which comprises treating textilematerials made from polyethylene-glycolterephthalates or their mixtureswith cellulose fibres or wool.

7. A process as claimed in claim 1, which comprises treating textilematerials dyed or printed with disperse dyestuffs with the solventmixture of claim 1.

References Cited UNITED STATES PATENTS 3,129,053 4/ 1964 Castle 8130.12,981,978 5/ 1961 Grifling 8Dig. 4 3,199,679 10/ 1965 Sayler 8142 DONALDLEVY, Primary Examiner U.S. Cl. X.R.

